Numbers in
the Air

Numbers stations are mysterious
shortwave radio stations, broadcasting streams of
numbers or letters using the phonetic alphabet,
by voice, Morse or digital tones. The messages
are usually groups of four or five numbers or
letters and are typically repeated by reading
each group twice or repeating the entire message.
These stations are unlicensed high power HF
transmitters, broadcasting worldwide in various
formats and languages.

They do this day and night on a
wide range of frequencies and it's been going on
for decades, yet no single private, commercial or
government agency ever stepped forward to
officially confirm that they are responsible for
these strange broadcasts of numbers. However,
today there is enough evidence that Intelligence
agencies use these numbers stations, also called
one-way voice link, to send encrypted operational
messages and instructions to their agents in
covert operations abroad.

The messages are broadcast on
very powerful shortwave transmitters with
frequencies ranging from 3,000 to 30,000 KHz. The
numbers or letters are spoken in many different
languages, usually a female voice, but sometimes
male or those of children. Many of the broadcasts
are mysterious mechanically or electronically
generated voices. The stations often use
introduction signals as a beacon, prior to a
actual message. These repeating phrases,
electronic sounds or music enable the receiver to
adjust his radio to the desired frequency. In
recent years, many numbers stations switched from
voice or Morse to digital tones.

Radio amateurs monitor these
broadcasts and they sometimes give nicknames to a
station, according to its typical introduction
phrase (e.g. the Cuban "Atencion"
station), prelude music (Swedish rhapsody) or
language of the voice (Bulgarian Betty). Some
stations are called counting stations, because of
their introduction signal. An example is the
Cuban "Atencion 1234567890".

The Cold War era, from the
1950s until the end of the 1980s, is known for
its numerous and very active numbers stations,
not by coincidence the heydays of espionage. Many
of the broadcasts came from the Eastern-block
countries, China and Cuba, but also from several
Western countries.

After the 1989 fall of the
Berlin Wall, the number of stations significantly
decreased from countries like East and West
Germany, Yugoslavia, Hungary or Bulgaria. The
voices of those stations were mostly Russian or
German. However, several decades after the end of
the Cold War, stations remain active in the
former Soviet-Union, Europe, and in North and
South America, and new stations continue to
appear all over the world.

Most numbers stations use a
basic format to send the streams of numbers or
letters. Some stations broadcast every day at a
fixed hour, and disappear after a few days or
weeks. Other stations have an irregular time
schedules and appear and disappear over time. One
of the most regular numbers stations ever was the
Lincolnshire Poacher (E3 Voice), named after the
English folk song that was used as its interval
signal. After transmitting the very recognizable
melody and a call-sign for about ten minutes, the
message was sent by an electronic
English-accented female voice in groups of five
figures. The station aired every day from the
1970s until 2008. A simple small shortwave radio
was sufficient to capture the Lincolnshire
Poacher. It is believed that the station
broadcast from the RAF Akrotiri basis in Cyprus
and that is was operated by the British Secret
Intelligence Service. Unfortunately, the world of
radio waves lost a true Cold War icon when the
station went off-air in 2008. Its Asian sister
station Cherry Ripe however is still active.

Why Numbers Stations

Although no government or legal
broadcaster ever acknowledged any involvement in
these broadcasts, it is obvious that the costs
and organization of such large-scale illegal
broadcasts can only be supported and approved by
government agencies. Countries like Russia, China
and the United States exploit large shortwave
antenna parks in their own country and at their
embassies abroad.

The content of the messages
appear to be a random series of numbers without
any logical order or meaning. It is confirmed in
several uncovered spy cases that these seemingly
random numbers are actually one-time-pad
encrypted messages. Numbers messages were used
extensively during the Second World War. The
British Special Operations Executive (SOE), the
American Office of Strategic Services (OSS) and
many other wartime intelligence agencies used
them to communicate with their espionage and
sabotage teams, operating behind enemy lines.

History has proven this to be a
most secure method. One-time pads are sheets or
booklets with keys that consist of series of
truly random numbers or letters. Enciphering and
deciphering a message only requires pencil and
paper and some basic calculations. Each message
is enciphered with a unique one-time pad which is
destroyed after one-time use. If properly
applied, one-time pad is the only system that is
proven to be mathematically unbreakable. Visit my
one-time
pad page for more info.

The one-way shortwave broadcast
has many advantages for Intelligence agencies.
Powerful shortwave transmitters reflect their
signal many times between the earth's surface and
the ionosphere, carrying them over very long
distances. This enables Intelligence agencies to
send messages to agents located in far away
countries. The many reflections also make it
difficult to accurately locate the transmitter
and find out who is broadcasting. The enormous,
almost global range of shortwave makes it
impossible to identify the country of
destination, let alone the person who receives
the message.

Therefore, there is little risk
of exposing the secret agent who receives a
message. A simple commercial shortwave
world-receiver can pick up a messages and the
agent doesn't need a compromising special
receiver or crypto equipment. He can easily carry
and hide a large number of one-time pads in small
booklets or on microfilm, and the manual one-time
pad system, although slow and elaborate, requires
nothing more than a pencil and paper. Therefore,
numbers stations are an ideal method of covert
one-way communication to illegal agents abroad.

Evidence for use as Spy
Stations

Over time, declassified
documents from court trials and Intelligence
agencies revealed the truth about these
mysterious numbers stations. They also show that
the era of spy stations and espionage is far from
over. This information enables us to discard all
stories about numbers stations being so-called
weather buoys, shipping reports or other
fairytales. Several spies have been caught in
possession of shortwave radios and one time pads.
Given the widespread and frequent use of numbers
stations, the published cases are undoubtedly
only the tip of the iceberg.

In 1962, Soviet GRU Colonel
Oleg Penkovsky was arrested by the KGB and
charged with espionage. During a search of his
Moscow apartment, the KGB found one-time pads,
instructions on how to receive and decipher
encrypted radio messages, including a
letter-to-digit checkerboard and a Morse cut
numbers table, a Sony shortwave radio, a Minox
camera and other spy equipment, cleverly hidden
inside a secret compartment in his desk.

Documents of the Ministerium
fur Staatssicherheit (Stasi) of the former German
Democratic Republic (East Germany) show
intercepted packets, destined for West German CIA
agents, operating in East Germany. They contain
one-time pads and instructions on how to receive
and decipher messages on shortwave radio. These
are published on the SAS und
Chiffrierdienst
website. The Stasi's foreign intelligence service
Hauptverwaltung Aufklärung (HVA) called their
own numbers stations Einseitiger operativer
Kurzwellenfunk or Welle 1 (lit. single-side
operational shortwave radio or wave 1). They also
used a speech and Morse generator to automate the
transmission of their messages. You can watch an
authentic speech generator
running and see how it is operated or listen to the voice output (mp3). This is the machine behind the
infamous East German lady. The machine was
labeled in English due to the exported to many
other Eastern-block countries.

Michael Michnowski defected
together with Stasi agent Werner Stiller from
East Germany in 1979. He wrote about the
preparations and the defection. In that story he
describes the covert communications with the
Bundesnachrichtendienst (BND), West-German
intelligence, and how they used a shortwave radio
to receive one-time pad encrypted instructions,
sent by BND numbers stations.

Jack Barsky, born as Albrecht
Dittrich in East Germany, was scouted by the
Stasi, recruited by the KGB and sent to the
United States under the false identity of Jack
Barsky. His spying career lasted from 1978 until
1988. Every Thursday at 21:15 Hrs Barsky tuned
his shortwave radio to a predetermined frequency
and listened for a so-called radiogram from the
KGB. These radiograms contained operational
instructions that were encrypted into digits and
sent in groups of five. A radiogram could take an
hour to receive and write down and three hours to
decrypt. Barskys KGB radiograms were
transmitted from Cuba towards the United States.
Watch Jack Barsky's
two-part interview
where he talks about the radiograms (in part
one).

In 1988 Vaclav Jelinek, a Czech StB spy who operated under the
false identity of Erwin van Haarlem, was arrested
by British Special Branch detectives while
receiving a numbers message on a shortwave radio
in his London apartment. One-time pads were found
on microfilm, hidden in bars of soap. The pads
enabled the detectives to decipher some of the
received messages, which were later used in
court. Jelinek was sentenced to ten years of
imprisonment.

More recently, there were
several spy cases in the United States, related
to Cuban numbers stations. In the 1998, the
so-called Cuban Five from the Wasp Network spy ring, agents
of the Cuban DGI (Dirección General de
Inteligencia), received instructions by
encrypted messages that were sent each day by the
Cuban HF numbers station "Atencion".

Another one was the Ana Belen Montes case, a senior US Defense Intelligence
Agency analyst, spying for Cuba. She was arrested
in 2001 and the federal prosecutors stated:
"Montes communicated with the Cuban
Intelligence Service through encrypted messages
and received her instructions through encrypted
shortwave transmissions from Cuba". More on
the Belen Montes case in this FBI affidavit
(pdf).

In 2006, Florida International
University professor Carlos Alvarez and his wife Elsa Alvarez were charged
with espionage and acting as agents for Cuba. The
US District Court Florida stated:
"Defendants would receive assignments via
shortwave radio transmissions. These messages
were encoded in five-digit groupings. Once
received, Defendants would input these coded
messages into their home computer, which was
equipped with decryption technology contained on
a diskette" More in the Alvarez sentencing.

US State Department official Walter Kendall
Myers and his wife
Gwendolyn Steingraber Myers were arrested in 2009
on charges of serving as illegal agents of the
Cuban government for nearly 30 years. They
acknowledged having received encrypted messages
from the Cuban Intelligence via a shortwave radio
they possessed. The Columbia State District Court
indictment stated that "Cuban intelligence
broadcasts encrypted shortwave radio messages in
Morse Code or by a voice reading numbers"
and also that "It was part of the conspiracy
that Cuban Intelligence would and did broadcast
shortwave messages in Morse code which were
receive by Kendall Myers". More about this
case in the Myers court
indictment.

From
Cold War to Cold Peace

Are numbers stations still
useful in this age of global communications,
Internet and satellite links? Yes! The so-called
end of the Cold War did not bring a significant
decrease in espionage activities. In the
contrary, the Cold War is merely replaced by a
Cold Peace where espionage is booming. In today's
world, with the globalization of economics,
politics and conflicts without borders, covert
and illegal agents of Eastern, Western, Asian and
Far East countries still operate extensively in
each others countries to gather Intelligence and
run operations. They still need a secure way to
receive their operational instructions and
messages. However, today, all modern
communication systems are controlled by computers
and are therefore by definition insecure.

Telephone, Internet and even
satellite transmissions can be monitored. E-mails
can be intercepted and read. Some government
agencies have the money and resources to monitor
communications and trace both sender and
receiver. An example is the huge ECHELON project
which globally intercepts and identifies all
kinds of communications. In times of conflict,
countries can simply block the Internet or other
communications, or even simply switch off
satellites. There have been successful tests to
destroy satellites with missiles, making
satellite communications unreliable during a
serious conflict. Or did you really believe to
continue using telephone or Internet between,
let's say, Russia and the United States, if they
where at war with each other?

Imagine a war broke out and
intelligence personnel are operating behind enemy
lines. The only secure and reliable way to
communicate with them would be the good
old-fashion long distance shortwave radio. But
even in times of peace, some covert operations
are so sensitive that discovering them would
bring governments big problems or embarrassment.
It is believed that some numbers stations
continuously send fake messages, just to keep the
lines open, ready for use. Those who monitor
these stations are unable to notice when a
station suddenly changes from sending random
numbers to operational encrypted traffic. A good
example is the Lincolnshire Poacher, sending
messages of 200 groups, each and every day, for
almost 40 years. Reasons enough why numbers
stations are still active and useful. With their
long and outstanding career of more than 70
years, the numbers stations have become an icon
of espionage.

And still, every single day,
numbers messages are transmitted all over the
world, spoken in English, Russian, Spanish,
Chinese and many other languages. Who's
broadcasting them and, even more intriguing,
who's listening to them...?